In systems with semiconductors, the impact of a high-energy particle can cause undesirable effects.
In particular, for cells or memory points, the impact of a high-energy particle may cause it to change state or stored value. For example, a stored bit with a value 1 may change to a value 0, and vice versa.
Hardening of electronic components against ionizing rays and high-energy particles is called a method of design, of production and of testing of electronic systems and components in order to make them resistant to the malfunctions and degradations caused by electromagnetic rays and energetic subatomic particles encountered during space or high-altitude flights, and in the environment of nuclear reactors, and even during military operations.
A singular effect may be caused when a single particle passes, usually a heavy ion or an energetic proton, and may cause transitory effects (software errors or SEU for “Single Event Upset”) and/or permanent effects (hardware errors or SEL for “Single Event Latchup”).
An SEU is typically materialized by the changing of logic state of a memory cell under the effect of a charged particle. It is a transitory effect that will be erased by the rewriting of the affected memory cell. Any electronic circuit that has memory cells is susceptible to experiencing SEUs.
Systems are known that use a Triple Modular Redundancy or TMR. Such systems essentially consist in tripling a memory cell or memory point and in including as an output of these three redundancy memory cells a voting element for fixing as an output the majority value amongst the three memory cells.
Thus, at the time of the impact of a high-energy particle causing an SEU and a change of state or of value of a memory cell, by using a voting element with a sufficiently high clock rate for the probability of two simultaneous SEUs out of at least two of the three redundancy memory cells is virtually zero, the impact is corrected by such a system.
The production of such systems is very costly.
Moreover, this type of system is difficult to implement when it is desired to perform RF (for radiofrequency) functions because of the spectral pollution generated by the clock for rating the refresh of the data or, for other applications, when the complexity of the triple modular redundancy or TMR with a voting system is not acceptable.